Note: Descriptions are shown in the official language in which they were submitted.
IMPROVED FLEXIBLE CONDUIT STRUCTURE
The present invention relates to a conduit
structure and more particularly, to a flexible conduit
structure comprised of a plurality of tubes for con~eying
a plurality of fluids to dental handpieces or the like.
Backaround of the Invention
certain medical and dental appliances, such as
dental handpieces, require the supply of multiple fluids
during their operation. For example, a dental handpiece
may require air to be supplied under pressure to drive the
turbine by which the dental burr or other tool is driven.
The dental handpiece may also be provided with outlets for
projection of cooling air and/or water upon a tooth as it
is being abraded by a dental burr driven by the handpiece.
In the case of the drive air, the exhaust air is sometimes
conveyed out of the mouth rather than being exhausted from
the turbine directly into the mouth. These fluids have
been conveyed to and from the mouth in flexible tubes and,
for convenience of handling and appearance, the tubes have
been bundled together. It is also commonplace to form
such bundles by extruding a plurality of tubes connected
by webs of the extruded material. As provided heretofore,
such webs provided a concave surface between adjacent
pairs of tubes which is undesirable in that foreign matter
may deposit therein.
It is, therefore, an object of the present
invention to provide a new and improved conduit structure
for conveying a multiple number of fluids to a medical or
dental appliance.
More particu]arly, it is an object of the present
invention to provide a conduit structure which is
substantially free of indentations on its exterior surface
in which foreign matter can collect.
Still another object of the invention is to
provide a conduit structure comprising multiple tubes
connected by webs wherein the webs are of lesser thickness
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along their juncture with each of the adjacent tubes
whereby the webs may be stripped from such tubes easily
and cleanly.
Other objects and advantages of the invention
will become more apparent hereinafter.
Summary o~ the Invention
In accordance with a preferred embodiment of the
invention, an extruded conduit structure is provided
comprising a cluster of at least three tubes connected by
wehs extending between adjacent pairs, the tu~es and webs
heing formed by simultaneous extrusion of a suitable
plastic through a suitable die. The outer surface of each
of the webs is convexly curved in an arc that is
substantially tangential with the outer surfaces of the
adjacent pair of tubes. The inner surface of each of the
webs is flat relative to the outer surface and forms a
cord of such arc whereby each of the webs will be of
minimum thickness along each of its junctures with the
adjacent webs. This construction substantially eliminates
any concave surfaces on the exterior of the conduit within
which foreign matter may collect and, because of the
thinner wall sections at the juncture of the webs with the
adjacent tubes, the webs can be easily stripped along the
tubes to expose the tube ends for connection to the
apparatus to which they are to be connected.
Brief Descri~tion of the Drawinqs
Figure 1 is a perspective view of a conduit
structure constructed in accordance with the present
invention and containing four tubes;
Figure 2 is an enlarged cross-sectional view of
the conduit structure of Figure 1;
Figure 3 is a perspective view of the conduit
structure of Figure 1 illustrating how the web between
tubes can be peeled back;
Figure 4 is an enlarged fragmentary end view of a
conduit structure made in accordance with the invention;
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Figure 5 is an end view of a conduit structure
made in accordance with the prior art; and
Figure 6 is an enlarged cross-sectional view of a
conduit structure havin~ three tubes and constructed in
accordance with the present invention.
Detailed Descri~tio of the Invention
Referring to Figures 1 and 2, therein is
illustrated a length of conduit structure 10 constructed
in accordance with the invention for use with a dental
handpiece and comprising wall means defining four tubes
12, 14, 16 and 18. Tubes 12 and 14 are of larger diameter
than tubes 16 and 18. Tube 12 is formed with an
identifying rib 20 along the length thereof and, in
accordance with custom, is utilized to convey drive air to
a dental handpiece. The tube 14 is provided for
conducting the exhaust drive air away from the dental
handpiece so that it may be exhausted at some remote
location. The tubes 16, 18 are provided for conveying air
and water, respectively, to the dental handpiece for the
purposes of cooling the work area in the tooth of a
patient. The conduit structure 10 is formed by extrusion
of a suitable extrudable material such as polyvinyl
chloride or polyurethane.
The tubes 12 and 14 are connected by a web 24,
the outer surface 26 of which is convexly curved
preferably on an arc such that its intersection with a
plane perpendicular to the axis 22 of the conduit
structure 10 defines an arc which is substantially
tangential with the outer surfaces of the tubes 12, 14.
The web 24 preferably is thinnest adjacent each of the
tubes 12, 14. In a preferred embodiment of the invention,
the inner surface 28 of the web 24 is such that it
intersects a plane perpendicular to the axis 22 along a
cord of the arc 26, the line of intersection being
substantially perpendicular to a radius of the arc
defining the outer surface 26 substantially at the
midpoint of the web. With this construction, the web will
zo~n~
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have a minimum thickness Tl at its juncture with adjacent
tubes 1~, 14 and a maximum thickness T2 at its midpoint.
Similarly, the tubes 14, 16 are connect~d by a
web 34, the tubes 16, 18 by a web 36, and the tubes 12, 18
by a web 3~. Each of the webs 34, 36, 38 is formed
preferably in the same manner as the web 24, i.e., with a
convex outer surface that is tangential with the surfaces
of the adjacent pairs of tubes and with an inner surface
that is flat such that the intersection of the
lo corresponding web with the adjacent tubes is thinnest
along the juncture of the web with the tubes adjacent
thereto. The construction of the webs whereby they are
thinner along their juncture points with the adjacent
tubes, permits the webs to be peeled back as indicated in
Figure 3, where a peeled back portion 40 of the web 24 is
illustrated, so as to expose the ends of the adjacent
tubes 12, 14. Likewise, the similar portions of the webs
34, 36 and 38 could be peeled back and thereafter all of
the web ends cut off leaving the ends of the tubes exposed
so that they may more conveniently be slipped onto the
cooperative fittings of a dental handpiece or the like.
The provision of the convex surfaces, such as the
surface 26, on connecting webs 24, 34, 36 and 38 of the
conduit structure, substantially reduces or eliminates the
presence of concave surfaces along the exterior of the
conduit structure within which foreign matter may collect.
Such foreign matter may include undesirable bacteria of
infectious diseases. In Fi~ure 5, for example, there is
shown in cross-section a prior art conduit structure of
which I am aware f~r use with a dental handpiece
comprising four tubes, including a tube 60 for drive air
and a tube 62 for exhaust air and which tubes are
connected by a web 64 which is of substantially uniform
thickness between the tubes 62, 64 and the outer surface
6~ which was concavely cur~ed between the tubes 62, 64 so
as to provide a substantial indentation of about 0.020
inches at its center extending along the length of the
conduit structure and in which foreign matter could
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collect. The indentations between the other pairs of
tubes ranged from 0.006 to 0.016 lnches.
As a practical matter, it is sometimes impossible
to extrude a tube with the exact desired configuration as
is shown in Figure 2. For example, in Figure 4, there is
shown an enlarged end portion of a conduit structure
including a tube 14' and a convex web 24' wherein the
convex outer surface 26' is not quite tangential with the
outer surface of the tube 14', thus forming a slight
indentation 70 which would extend along the length of the
tube and in which some foreign matter might conceivably
collect~ Thece I have observed to be only betwe~n 0.003
and 0.007 inches deep. However, indentations of such
depth have a much smaller volume than the indentations in
the prior art structure of Figure 5, so as to collect less
foreign material and because they are shallower are much
more easily cleaned and, thus, present much less of a
health hazard.
Turning now to Figure 6, there is shown therein a
conduit structure 78 made in accordance with the invention
consisting of three tubes and connecting webs including a
large tube ~0 which may be used for conveying, for
example, drive air to a handpiece and two smaller tubes
82, 84 for conveying coolant water and coolant air,
respectively, to a handpiece. The tubes 80, 82 are
connected by a web 86, the tubes 82, 84 by a web 88, and
the tubes 80, 84 by a web 90. Each of such webs is formed
with an arcuate convex outer surface that is substantially
tangential to the adjacent pairs of tubes so as to avoid
the creation of indentations on the outer surface of the
conduit, and with an inner surface preferably flat and
chordal to the arc of the web outer surface so that the
webs are each thinner adjacent the adjacent tubes in the
same manner as the embodiment of Figures 1 to 4.
As indicated above, the conduit structure of the
invention is adapted to be formed by extruding a suitable
thermoplastic material through a die which, as will be
known to those skilled in the art, will have a
20~
configuration substantially complementary to the
configuration of the conduit structure. In accordance
with conventional practice, the hot, extruded structure
will be rapidly cooled by immersing it in water. As the
structure is extruded it is preferred that air be blown
into the center of the structure so as to maintain a small
positive pressure of about five pounds per square inch so
as to maintain the webs in a distended configuration as
shown in the drawings in Figures 1-4 and 6 and prevent
their collapsing inwardly as in the prior art structures
as shown in Figure 5.
Having illustrated and described the preferred
embodiments of the present invention, it will be apparent
that the invention can be modified in arrangement and
detail. I claim all such modifications as come within the
ambit of the attached claims.
